A mental illness that causes people to have severe high and low moods. People with this illness swing from feeling overly happy and joyful (or irritable) to feeling very sad and hopeless (or happy). In between these mood swings, a person's moods may be normal.
classified as a type of affective disorder (or mood disorder) that goes beyond the day's ordinary ups and downs. Manic depression is characterized by periodic episodes of extreme elation, elevated mood, or irritability (also called mania) countered by periodic, classic depressive symptoms.